The minutes seem like hours in the Trump administration. Every day brings a fresh deluge of alarming developments. Has it only been three weeks? Can the country survive four years of this?

The most hopeful sign so far arrived Thursday, with the Latin phrase per curiam: Not only did the federal appeals court reject the Trump administration’s highhanded argument that its immigration order was not subject to judicial review, it did so unanimously.

A judge appointed by President George W. Bush joined two judges appointed by Democratic presidents (Barack Obama and Jimmy Carter) to uphold a decision by a district court judge named by Bush. The appeals court spoke as one. Not as partisans or ideologues but as judges, calmly and convincingly applying the law in State of Washington v. Donald J. Trump.

Of course, the court acknowledged, judges “owe substantial deference to the immigration and national security policy determinations of the political branches.” But the Trump administration, the court said, was making a far more audacious argument — not that the court should refrain from substituting its judgment for the president’s, but that it had no business reviewing his action in the first place.

The court, accurately, characterized the administration’s position: “The President’s decisions about immigration policy, particularly when motivated by national security concerns, are unreviewable , even if those actions potentially contravene constitutional rights and protections.”

Not only that, as the court put it, the Trump administration “asserts that it violates separation of powers for the judiciary to entertain a constitutional challenge to executive actions such as this one.” In other words, even to consider the state’s argument against the order would be an unconstitutional incursion on presidential authority.

The judges were having none of it. The administration’s argument, the court said, “runs contrary to the fundamental structure of our constitutional democracy.”

Rage he might, because the implications of the court’s action resonate far beyond the immigration order itself. Other courts will hear other cases involving Trump actions yet to come; a Supreme Court eventually stocked with a Trump-appointed justice could have the final word.

Yet the 9th Circuit ruling, suffused with bristling at the notion that courts should remain supine in the face of claims of unbridled executive power, offers an illustration of judicial willingness to provide a needed brake on Trumpian overreach — and, perhaps, a foreshadowing of similar actions to come.

Consider that at oral argument, the Bush-appointed judge, Richard R. Clifton, seemed most inclined to side with the government. It is not fanciful to imagine that the sweeping nature of the government’s claims and Trump’s out-of-court attacks on the judiciary had the boomerang effect of leading Clifton to align with the two Democratic appointees.

Judges may not cite presidential tweets and remarks, but it is naive to think that they escape judicial notice. “I don’t want to call a court biased, but courts seem to be so political,” Trump complained the day after the oral argument. A two-Democrats-to-one-Republican ruling would have buttressed that view. Did worrying about such implications tip Clifton to rule against the president?

There is a subtle Newtonian logic in the real-world operation of the separation of powers. Every overreaction provokes a reaction, even if not equal and opposite. When the executive goes too far, especially when Congress seems compliant, the courts tend to be more willing to step in. When a president disparages the judiciary, when he speaks and operates in a way that seems heedless of constitutional norms, judges are more on guard, and less inclined to be reflexively deferential.

So it has been a long three weeks; many dangers loom. The reasons to worry are ample, from the president’s latitude in conducting foreign policy and military operations to the acquiescent Republican congressional majority. Still, the framers crafted a resilient system of checks and balances that can protect us from some, although by no means all, of Trump’s excesses.

On that score, the appeals court’s action is not merely a teachable moment for the country — it is a reassuring one, at a time when that is sorely needed.